var index_bgm = document.getElementsByClassName("index-bgm")[0];

index_bgm.children[0].addEventListener("click",function(){
	if(this.nextElementSibling.innerHTML == "TURN OFF"){
		this.nextElementSibling.innerHTML = "TURN ON";
		this.children[0].src = "img/index-bgm1.png";
		this.className = "index-bgm-pic-active";
	}
	else{
		this.nextElementSibling.innerHTML = "TURN OFF";
		this.children[0].src = "img/index-bgm2.png";
		this.className = "index-bgm-pic";
	}
})


function vis(){
//	var start = document.getElementById("start").querySelectorAll(".page3-you");
//	var guize = document.getElementById("guize").querySelectorAll(".page3-you");
//	
	var page3_you = document.querySelectorAll(".page3-you");
	var arr = [],arr1 = [];
	for(let y=0;y<page3_you.length;y++){
		if(y%2==1){
			arr[y] = setTimeout(function(){
				page3_you[y].style.visibility = "hidden";
				clearTimeout(arr[y]);
			},300);
			arr1[y] = setTimeout(function(){
				page3_you[y].style.visibility = "visible";
				clearTimeout(arr1[y]);
			},800);
		}
		else{
			page3_you[y].style.visibility = "hidden";
			arr1[y] = setTimeout(function(){
				page3_you[y].style.visibility = "visible";
				clearTimeout(arr1[y]);
			},500);
		}
	}
}



